1. Field of Invention
The present invention relates to a laser welding device, and more particularly, to a laser welding device which welds parts, such as a vehicular lamp and a metal bipolar plate of a fuel cell which require air tightness, using laser.
2. Description of Related Art
Generally, a laser welding may be classified into a keyhole welding which uses energy multiple reflection and absorption in a focal section of a laser beam and a conduction welding which uses heat conduction in a non-focal section of the laser beam.
In a general laser welding system for welding materials, such as a steel plate or an aluminum alloy sheet, using the laser beam, a laser head is mounted at a leading end of an arm of a robot and the laser head is connected to a laser oscillator.
The laser head irradiates the laser beam while moving along a welding pattern of a material by the robot which is operated by a robot controller to perform a welding operation of a welding object.
Meanwhile, among vehicle parts, parts requiring air tightness which is an important factor of quality, for example, parts such as a vehicular lamp or a metal bipolar plate of a fuel cell are welded by mainly using the laser beam.
For the laser welding of the parts, it is important to make a gap between at least two sheets of parts zero. To this end, the related art uses a pressing jig pressing the parts which are the welding object and making the gap between the parts zero and a laser head moving in a multi axis.
Herein, the laser welding using the pressing jig may be divided into an open loop welding scheme and a closed loop welding scheme depending on a welded portion pattern.
The open loop welding scheme performs the laser welding on parts depending on a welded portion pattern with a predetermined opened section in the state in which the parts are pressed with the pressing jig. Further, the closed loop welding scheme performs the laser welding on parts depending on a welded portion pattern without the opened section in the state in which the parts are pressed with the pressing jig.
However, in the case of the closed loop welding scheme according to the related art, the laser head irradiates the laser beam while moving along the welded portion pattern from an outside of the pressing jig, such that it is not easy to implement the welded pattern portion of the closed loop due to an interference between the pressing jig and the laser head
To improve this, the related art attaches the laser head to a multi-axis robot and uses an expensive pressing jig pressing the parts to implement the welded portion pattern of the closed loop, but it is difficult to rapidly and uniformly perform the laser welding and facility investment cost increases.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.